Understanding the tool wear mechanism during thermally assisted machining Ti-6Al-4V

Thermally assisted machining is an emerging manufacturing process for improving the productivity when machining many difficult-to-cut engineering materials. Traditionally the process is reserved for very hard and high strength materials where abrasive and notching wear mechanisms cripple tool longevity. Recently there has been interest in using the process to machine titanium alloys and published reports indicate that machinability is improved, namely though a reduction in cutting forces. However, there is still ambiguity about whether the process is beneficial for tool life and the specific wear mechanisms for carbide tooling remain unknown. This work characterises the tool life and wear mechanism for two uncoated carbide tools when turning Ti-6Al-4V at high speed. While it is observed that thermally assisted machining reduces the cutting forces, it is found that the process has a deleterious effect on tool life because the dominant wear mechanism associated with diffusion is exacerbated during thermally enhanced machining. The process is compared against coolant technologies from the literature using identical tooling and cutting parameters and it is found that cooling the tool suppresses adhesion-diffusion wear and significantly prolongs tool life.